Background The feasibility of using landiolol hydrochloride in multislice computed tomography (MSCT) coronary angiography (CAG) was investigated in the present study. Methods and Results Landiolol hydrochloride was continuously administered intravenously to 145 patients before starting MSCT CAG. Hemodynamic changes [blood pressure (BP), heart rate (HR)], adverse effects, image quality using a 5-point scale, and accuracy of detecting significant stenoses (≥50% reduction in lumen diameter) were evaluated. HR was significantly reduced during injection, and quickly recovered after cessation of administration, of landiolol hydrochloride. Neither significant changes in BP nor adverse effects occurred. Among visible segments, 1,869 (94%) displayed an excellent (83%) or good (11%) image quality. Diagnostic accuracy was evaluated in 39 of 145 patients who underwent invasive CAG within 3 weeks after MSCT. The sensitivity, specificity, positive predictive value, and negative predictive value of MSCT CAG for detection of significant stenoses in assessable segments were excellent (per artery: 94%, 98%, 92%, and 100%; per segment: 92%, 98%, 94%, and 96%, respectively). Conclusions Intravenous administration of landiolol hydrochloride reduces HR without a significant reduction in BP, which enables favorable image quality and diagnostic accuracy without adverse effects, making this agent feasible as a premedication for MSCT CAG. (Circ J 2008; 72: 1814 - 1820)